1. Field of the Invention
The present invention relates to an apparatus for sending and receiving light signals representing information. More particularly, the present invention relates to an apparatus for sending and receiving light signals along a circular path.
2. Description of the Related Art
The invention relates to an apparatus for sending and receiving light signals along a circular path. Rotating light signals are provided, e.g., as part of a telemetering apparatus for medical examination or research purposes. The light signals represent measurement information. Telemetering devices typically comprise a rotating sender support with a plurality sender devices for transmitting signal light, and a stationary detecting receiver device disposed on a circle. The sender device is positionally fixed on the support, and the circle is parallel to the circular path over which the sender device is rotated. The sender of the sender device is disposed at a distance from the receiver device.
A telemetering apparatus of this type is shown, for instance, in Eur. Patent No. EP-A-0 381 786, where the device is used for computer-aided tomography in medical practice. The sender support is comprised of a support ring or hollow ring which surrounds the patient. A plurality of rotationally fixed sender devices are disposed around said ring. The light emitted by each such sender has a fan-like emission pattern. A circularly disposed receiving device comprising a single detector is provided in the plane of the ring. The distance between the detector and the senders varies, but is generally quite large. However, this known apparatus is costly because it requires a plurality of senders, and is subject to interference and other problems because of the appreciable and varying distance between the senders and the detector.
Other devices are used to send and receive a light beam, wherein the beam is moved along a straight line. The sender device has only one sender for said light beam, and the receiver device is comprised of a fluorescing fiber-optic disposed in a straight line. A detector is located at each of the two ends of the fiber, wherewith the beam emitted from the sender impinges on the fiber-optic fiber at approximately a right angle thereto and the sender is disposed very close to the fiber-optic fiber. This arrangement serves to determine the position of the sender support along the straight fiber-optic fiber, i.e., the position of the sender between the two detectors. Thus, this apparatus also fails to provide interference-free, problem-free, precise transmission of a continuously changing sequence of informational signals from a medical examination apparatus.